As various electronic apparatuses, such as mobile phones and video cameras, have recently had small sizes and high functions, rotary actuators and input devices have been demanded to perform various operations of the apparatuses with a preferable feeling during operation.
FIGS. 4 and 5 are a front sectional view and an exploded perspective view of a conventional rotary actuator 6, respectively. Roller 1 has a substantially columnar shape and is made of metal or insulating resin. An outer circumferential surface of roller 1 has recesses. Roller 1 has center shafts 1A protruding from both ends of roller 1. Ring magnet 2 is alternately magnetized to S-poles and N-poles with predetermined angular pitches. Ring magnet 2 is fixed to each end of center shafts 1A of roller 1. Roller 1 is accommodated between upper cover 3 and lower cover 4 while center shafts 1A are rotatably supported by bearings 3A and 4A having substantially arcuate shapes. Plural fixed magnets 5 face ring magnets 2 by predetermined gaps provided at both ends of roller 1 with magnetic poles of ring magnet 2 and fixed magnet 5 having the same polarity face each other, thus providing rotary actuator 6.
FIG. 6 is side sectional view of input device 501 including rotary actuator 6. Plural wiring patterns are formed on upper and lower surfaces of wiring board 7. Wiring board 7 is located under rotary actuator 6. Magnetic detector 8, such as a Hall element, is mounted on the upper surface of wiring board 7. Magnetic detectors 8 face ring magnets 2 with predetermined gaps, thus providing input device 501.
Input device 501 is mounted to an operating section of an electronic device, such as a mobile phone, including a display, such as a liquid crystal display, and magnetic detector 8 is electrically connected to an electronic circuit of the electronic device via the wiring patterns.
An operation of input device 501 will be described below. While plural menus, such as names, or a cursor, are displayed on the display of the electronic device, roller 1 is rotated in left or right directions to rotate ring magnets 2. Since two ring magnets 2 are alternately magnetized to S-poles and N-poles deviating slightly from each other in angle by a predetermined angular phase difference, ring magnets 2 produce magnetic fields changing in different phases according to the rotation. Magnetic detectors 8 detect the change of the magnetic fields, generate pulse signals having phases different from each other, and send the signals to the electronic circuit of the electronic device.
The electronic circuit detects the direction and angle of the rotation of roller 1 based on the pulse signals, and moves the cursor on the menus on the display in vertical or horizontal directions, thereby allowing the menus, such as names, to be selected.
When roller 1 is rotated, this rotation produces attractive repulsive forces between ring magnet 2 and fixed magnet 5 facing each other. The attractive and repulsive forces provide generate click feeling, thus providing preferable, clear operation feeling.
Roller 1 rotates while center shaft 1A of roller 1 is supported by bearings 3A and 4A of upper cover 3 and lower cover 4, a friction produced between center shaft 1A and bearings 3A and 4A may cause a user to feel that roller 1 rubs.
Ring magnet 2 producing a larger magnetic field allows magnetic detector 8 to detect the direction and angle of the rotation of roller 1 more accurately, but also increases the attractive and repulsive forces between ring magnet 2 and fixed magnet 5. This may cause a rotation noise due to a shock when roller 1 is operated. Thus, conventional rotary actuator 6 can hardly operate with a preferable operation feeling.